CSF shunt valve

ABSTRACT

The CSF shunt valve includes an elongate, hollow housing and a valve unit disposed within the housing. A plurality of exit ports are formed along the wall of the housing, and a plurality of bleeder ports are formed on the bottom of the housing. The valve unit includes at least one regulating mechanism disposed within the housing. Each regulating mechanism includes an obstructing member operatively attached to a spring. The spring is compressible within a predefined range of fluid pressure. The obstructing member compresses the attached spring in response to fluid pressure acting thereon, opening the exit ports for fluid being drained. The spring-biased obstructing members facilitate self-adjustment for drainage flow. Although arranged in series, the range limits are not continuous with subsequent springs, which safeguards against transient spikes in fluid pressure and ensures independent compression of subsequent springs in response to the predefined limits of pressure for that spring.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to medical devices, and particularly to aCSF (cerebrospinal fluid) shunt valve that is self-regulating andresponsive to pressure differentials from the fluid being drained orshunted.

2. Description of the Related Art

Obstruction of cerebrospinal fluid (CSF) or its malabsorption leads tointracranial accumulation of CSF resulting in increased intracranialpressure (ICP) or hydrocephalus. This condition requires drainage orshunting of the CSF. As with many medical conditions, the ICP varies ina case-to-case basis, taking into consideration many variables, such asthe individual's age, gender, medical history and the like. Generally,the ICP can vary anywhere between 0-20 mm Hg.

Typically, a sterile internal system through a catheter is used to shuntCSF into a body cavity such as the right atrium of the heart, pleuralcavity or most commonly, the peritoneal cavity. An essential componentto this procedure is a valve situated along the drainage catheter toprevent excessive drainage. Proper shunt selection usually requiresaccurate ICP measurements and a precision opening pressure valve or aprogrammable valve. However, the most commonly used valves are valvespreset on one of the following differential pressure(s) (DP): low (<7mmHg), medium (7-11 mmHg), or high (>11 mmHg). While functional, thesevalves can be subject to complications for the patient when the presumedpressure proves to be inaccurate, leading to improper performance ofshunts, such as under- or over-drainage, necessitating replacement ofthe valve. Moreover, frequent monitoring and changes of the valve may benecessary when accounting for the potential changes in intracranial DP,especially since the pressure can change over time.

In light of the above, it would be a benefit in the medical arts toprovide a valve with more universal application that regulates flowdynamically for a wide range of pressures. Thus, a CSF shunt valvesolving the aforementioned problems is desired.

SUMMARY OF THE INVENTION

The CSF shunt valve includes an elongate, hollow housing and a valveunit disposed within the housing. A plurality of exit ports are formedalong the wall of the housing, and a plurality of bleeder ports areformed on the bottom of the housing. The valve unit includes at leastone regulating mechanism disposed in series within the housing. Eachregulating mechanism includes an obstructing member operatively attachedto a spring. The spring is compressible within a predefined range offluid pressure. The obstructing member compresses the attached spring inresponse to fluid pressure acting thereon, opening the exit ports forfluid being drained. The spring-biased obstructing members facilitateself-adjustment for drainage flow. Although arranged in series, therange limits are not continuous with subsequent springs, whichsafeguards against transient spikes in fluid pressure and ensuresindependent compression of subsequent springs in response to thepredefined limits of pressure for that spring.

These and other features of the present invention will become readilyapparent upon further review of the following specification anddrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an environmental, perspective view of a CSF shunt valveaccording to the present invention.

FIG. 2A is an axial section view of the CSF shunt valve of FIG. 1, shownwith the flow regulating units in a fully extended position.

FIG. 2B is an axial section view of the CSF shunt valve of FIG. 1, shownwith the flow regulating units in a compressed position.

FIG. 3A is a front view of the CSF shunt valve of FIG. 1.

FIG. 3B is a front view of an alternative embodiment of a CSF shuntvalve according to the present invention, the valve housing having slotsinstead of apertures.

FIG. 4A is an axial section view of another alternative embodiment of aCSF shunt valve according to the present invention.

FIG. 4B is a top view of one of the disks used in the CSF shunt valve ofFIG. 4A.

FIG. 5A is an axial section view of an alternative embodiment of a CSFshunt valve according to the present invention, shown with the flowregulating units in a fully extended position.

FIG. 5B is an axial section view of the CSF shunt valve of FIG. 5A,shown with the flow regulating units in a fully compressed position.

FIG. 6 is a perspective view of another alternative embodiment of a CSFshunt valve according to the present invention, shown with theprotective, outer sleeve broken away and partially in section.

FIG. 7 is an axial section view of a further alternative embodiment of aCSF shunt valve according to the present invention.

FIG. 8 is an axial section view of a still further alternativeembodiment of a CSF shunt valve according to the present invention.

Similar reference characters denote corresponding features consistentlythroughout the attached drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The CSF shunt valve, a first embodiment of which is generally referredto by the reference number 10, provides self-regulating flow of CSF thatvaries depending upon the pressure of incoming fluid flow. As best seenin FIGS. 1, 2A and 2B, the CSF shunt valve 10 is configured to bedetachably mounted to a ventricular catheter C. The CSF shunt valve 10includes an elongate, hollow valve housing 12 defining an innercollecting chamber 14. A valve unit 20 is disposed inside the collectingchamber 14. The valve unit 20 regulates flow of CSF, while thecollecting chamber 14 permits accumulation of the CSF for temporarystorage and drainage through the valve unit 20.

As best seen in FIG. 3A, the valve housing 12 is constructed as anelongate, substantially cylindrical tube having an open end forselective connection to the catheter C, the opposite end beingsubstantially closed. A plurality of exit ports or holes 16 are formedradially in the cylindrical sidewall of the housing 12, and a pluralityof bleeder ports or holes 18 are formed radially in the bottom chamberof the housing 12.

The valve unit 20 is configured as a pressure sensitive, passive meansof increasing or decreasing the exit area for the incoming fluid inresponse to the fluid pressure acting on the valve unit 20. The valveunit 20 includes a multiple-stage mechanism for revealing the radialexit ports 16 during operation in the form of a plurality ofspring-biased obstructing members, such as discs, arranged in serieswithin the collecting chamber 14. These mechanisms can also be construedas regulating mechanisms. As best shown in FIGS. 2A and 2B, the valve 10is constructed as a three-stage mechanism having a first disc 22, asecond disc 24, a third disc 26, a first spring 23 disposed between thefirst disc 22 and the second disc 24 and operatively connected to bothfirst and second discs 22, 24, a second spring 25 disposed between thesecond disc 24 and the third disc 26 and operatively connected to bothsecond and third discs 24, 26, and a third spring 27 disposed betweenthe third disc 26 and the bottom of the housing 12.

Each spring 23, 25, 27 is constructed with a spring constant designed tocompress within a predetermined range of pressure acting on the valveunit 20. The first spring 23 is compressible within a range of 3-5 mmHg,the second spring 25 is compressible within a range of 7-9 mmHg, and thethird spring 27 is compressible within a range of greater than 11 mmHg.These pressure ranges can be varied according to the needs of the user.Preferably, the pressure ranges for each spring are not consecutive,i.e. the pressure range from one spring to another is not continuouslysequential.

The above pressure range gap between successive springs, as well as theset pressure range in the first spring 23, provides several benefits.One benefit prevents anti-siphoning of the CSF fluid being drained byforcing the pressure to be at or above the preset pressure limits priorto any movement of the discs 22, 24, 26. These pressure range gaps alsopermit the fluid pressure to normalize in order to resist sudden changesin transient pressure until the fluid pressure reaches or exceeds thepreset pressure for the subsequent spring. The pressure requirement forthe next spring in the series also provides safeguards from much higherpressure buildup. In other words, the serial arrangement of the springs23, 25, 27 and the preselected range of pressures for each springprovide self-regulating features for controlling the pressures acting onthe valve unit 20, thereby insuring efficient and optimum drainage ofCSF.

In use, as the fluid enters the valve housing 12, the fluid causespressure to build on the first disc 24. When the pressure reaches thepreselected lower limit of pressures for the first spring 23, the firstdisc 22 begins to compress the first spring 23. Continual or suddenbuildup of pressure causes the first spring 23 to be compressed furtheruntil the spring 23 is fully compressed, which occurs at or above themaximum limit of pressure for the first spring 23. Whenever the pressurereaches the minimum or is greater than the minimum pressure for the nextspring 25 in the series, the second disc 24 begins to compress thesecond spring 25. This process repeats for the third disc 26 and thirdspring 27 whenever the fluid pressure is at or greater than the minimumpressure for the third spring 27. The depiction in FIG. 2A shows thevalve unit 20 in the normal, fully extended position, while thedepiction in FIG. 2B shows the valve unit in the fully compressedposition, where CSF pressure is greater than 9 mmHg.

As the discs 24, 26, 28 progressively compress within the collectingchamber 14 in response to increasing pressure, the retracting motion ofthe discs 24, 26, 28 increasingly opens up more of the exit ports 16.Preferably, the number and dimensions of the radial exit ports 16 form atotal exit area for the fluid being drained. This total exit areacorresponds to the cross-sectional area of the lumen of the catheter C.For example, if the catheter C has a 4 mm diameter lumen, the CSF shuntvalve 10 would include sixteen exit ports 16, each exit port 16 having a1.0 mm diameter (catheter lumen has a cross sectional area ofπr²=π2²=12.57 mm²; each exit port has a cross-sectional area of12.57/16=0.785 mm²; each exit port has a radius r=√{square root over(A/π)}=√{square root over (0.785/π)}=√{square root over (0.25)}=0.5 mm).The exit holes 16 are preferably arranged along the length of the valvehousing 12 in series, spaced apart at equal distances between the normalposition of the valve unit 20 (as shown in FIG. 2A) and the fullycompressed position (as shown in FIG. 2B). This arrangement allows thefluid to drain through the exit ports 16 in proportion to the incomingpressure and the corresponding depressed level of the valve unit 20.Additionally, the arrangement resists over-drainage in case of increasedrate of fluid egress. The plurality of bleeder ports 18 located at thebottom of the valve housing 12 allows the fluid to freely flow in andout of the collecting chamber 14, preventing air pressure between thethird disc 26 and the closed end of the valve housing 12. With the abovemultiple stages of compressibility, it can be seen that the valve unit20 permits dynamic self-adjustment for fluid egress, eliminating theneed for constant monitoring or adjustment of the CSF shunt valve 10.

An alternative embodiment of a CSF shunt valve having a different valvehousing 12 a is shown in FIG. 3B. In this embodiment, the valve housing12 a includes at least one elongate exit slot 16 a formed along thelength of the valve housing 12 a. The exit slots 16 a function the sameas the plurality of exit ports 16, i.e., the fluid exit area increasesthe further the discs 22, 24, 26 compress due to the incoming fluidpressure. In light of this, the exit slots 16 a are preferablydimensioned in a similar proportional manner as the exit ports 16 suchthat the total exit area thereof is equal to the total cross-sectionalarea of the lumen in the catheter C.

Another alternative embodiment of the CSF shunt valve 100 is shown inFIGS. 4A and 4B. In this embodiment, the CSF shunt valve 100 includesfeatures for more stable operation of the valve unit 120. Much like theCSF shunt valve 10, the CSF shunt valve 100 includes an elongate, hollowvalve housing 12 defining an interior collecting chamber 14; a valveunit 120; a plurality of exit ports 116 and a plurality of bleeder ports118. However, the CSF shunt valve 100 also includes a plurality ofelongate guide rails 130 disposed inside the collecting chamber 114.

The valve unit 120 includes a first disc 122 connected to a first spring123 and a second disc 140 connected to a second spring 141, the seconddisc 140 and the second spring 141 being attached to the first disc 122and the first spring 123 in series. Unlike the previous embodiment, eachdisc 122, 140 includes a plurality of guide notches 124, 142 formed onthe periphery thereof. The notches 124, 142 are constructed to slidealong the guide rails 130 so that the respective discs 122, 140 slide ina stable manner during operation, i.e., the discs 122, 140 are preventedfrom tilting due to the engagement between the guide notches 124, 142.Preferably, the first disc 122 is solid, providing a non-porous surfacefor receiving the full effect of the pressure from the incoming fluid.Any subsequent discs in the series, such as the second disc 140, can beprovided with a plurality of perforations 143 that allow flow of any ofthe fluid flowing past the first disc 122 or accumulated within thecollecting chamber 114. It is noted that while the valve unit 120utilizes two biased discs, the CSF shunt valve 10, 100 and any of theother embodiments disclosed herein can be constructed with any number ofspring-biased discs or similar constructions that provide presetcompression characteristics that depend upon the incoming fluidpressure.

A further alternative embodiment of the CSF shunt valve 200 is shown inFIGS. 5A and 5B. In this embodiment, the valve unit 220 for the CSFshunt valve 200 incorporates spring-biased balls instead of discs. Muchlike the previous embodiments, the CSF shunt valve 200 includes anelongate, hollow valve housing 212 configured to be detachably mountedto a catheter C, the housing 212 defining an interior collecting chamber214, and the valve unit 220 disposed in the collecting chamber 214.

The valve unit 220 includes an elongate, tubular sub-housing 221integral with the fluid inlet end 201 of the housing 212. Thesub-housing 221 houses a first ball 222, a first spring 223, a secondball 224, a second spring 225, a third ball 226 and a third spring 227,all operatively connected to each other in series. A plurality of exitports 216 are formed along the wall of the sub-housing 221.

As with the previous embodiments, each ball and spring set, e.g., thefirst ball 222 and the first spring 223, is constructed to becompressible within a preselected range of fluid pressure. In thenormal, non-draining position of the valve, all the springs 223, 225,227 are uncompressed, and the first ball 222 blocks the inlet end 201,as best seen in FIG. 5A. When fluid is introduced through the inlet end201 at a given pressure, the springs 223, 225, 227 serially compress inreaction to the pressure acting on the first ball 222. This reaction issubstantially the same as with the biased discs in the previousembodiments. The arrangement and dimensions of the exit ports 216provide the desired proportionate egress of fluid out of the sub-housing221 into the collecting chamber 214. The bottom of the sub-housing 221can include at least one bleeder port 218 permitting fluid flow betweenthe sub-housing 221 and the collecting chamber 214. The first ball 222is solid, while the second and third balls 224 and 226 are fenestratedto provide easier flow of fluid within the sub-housing 221.

A still further alternative embodiment of the CSF shunt valve 300 isshown in FIG. 6. In this embodiment, the CSF shunt valve 300 isconstructed to be more durable and functional, especially in times ofunavoidable accidents. As shown, the CSF shunt valve 300 includes anelongate housing 312, a plurality of exit ports 316, a plurality ofbleeder ports 318, and at least one elongate exit slot 317. Although notshown, any of the previously described valve units 20, 120, 220 can beprovided in the housing 312. The housing 312 is reinforced and protectedby an outer sleeve 350 attached to the housing 312. The outer sleeve 350surrounds the exterior wall of the housing 312 and is dimensioned toprovide an annular gap between the outer sleeve 350 and the housing 312.The outer sleeve 350 includes a plurality of reinforcing rings 352attached to the housing 312 by a plurality of radial members or bars353, 354. In use, the outer sleeve 350 protects the valve 300 from theenvironment, e.g., inadvertent impact on the valve 300 and otherexternal hazards, while facilitating egress of fluid being drained.

A still further alternative embodiment of the CSF shunt valve is shownin FIG. 7. This embodiment has a catheter integrated with a CSF shuntvalve according to the teachings above. As shown, the CSF shunt valve400 includes an elongate, hollow housing 412 containing a valve unit 420therein. A plurality of exit ports 416 and bleeder ports 418 permitdrainage of incoming fluid. The housing 412 is integrally attached to orformed on a bulbous, outer drain section 450 of a catheter C. The drainsection 450 surrounds the housing 412 within an interior chamber thatcaptures the fluid being drained.

A still further alternative embodiment of the CSF shunt valve 500 isshown in FIG. 8. This embodiment is similar to the CSF shunt valve 200,and it is noted that similar reference numbers have been used todesignate similar features. However, unlike the CSF shunt valve 200, theCSF shunt valve 500 utilizes a single ball 522 and a single springwithin the tubular sub-housing 521. The ball 522 is a solid balloperatively connected to a single spring. The single spring is dividedinto three different, pressure-sensitive regions or sections, i.e., afirst spring section 523, a second spring section 525, and a thirdspring section 527, representing three different stages ofcompressibility. Each section 523, 525, 527 is constructed to becompressible within predefined limits of fluid pressure, similar to theseparate springs 223, 225, 227 in the CSF shunt valve 200, where thefirst spring section 523 compresses within predefined lower limits ofpressure, the second spring section 525 compresses within predefinedintermediate limits of pressure, and the third spring section 527compresses within predefined higher limits of pressure. Preferably, thepressure ranges for each spring section are not consecutive, i.e. thepressure range from one spring section to another is not continuouslysequential. During use, each section 523, 525, 527 compress serially inresponse to the pressure of the incoming CSF fluid.

It is to be understood that the CSF shunt valve 10, 100, 200, 300, 400,500 encompasses a variety of alternatives. For example, the CSF shuntvalve 10, 100, 200, 300, 400, 500 can be constructed from a variety ofmedical grade materials, such as plastics, metal, composites, andcombinations thereof. The dimension and shape of the exit ports can bevaried, so long as they provide the desired fluid flow for the drainage.Moreover, the patterned arrangement of the exit ports can be varied, solong as they provide the desired exit area corresponding to the fluidpressure. Furthermore, any of the CSF shunt valve 10, 100, 200, 300, 400can be provided with a compressible spring having multiple stages ofcompressibility along progressive sections thereof similar to thesingle, multi-stage spring in the CSF shunt valve 500.

Various different forms of springs such as leaf springs, torsionsprings, cantilevered springs and the like can also be utilized. Withrespect to the coil springs shown in the drawings, the coil springs canbe constructed with varying length, pitch and spring constants toprovide the desired compressibility as well as control thereof.

It is to be understood that the present invention is not limited to theembodiments described above, but encompasses any and all embodimentswithin the scope of the following claims.

I claim:
 1. A CSF (cerebrospinal fluid) shunt valve, comprising: anelongate, hollow housing adapted to be attached to a catheter having alumen defining a cross-sectional area, the housing having a fluid inletend, a sidewall and a bottom; at least one exit port formed in thesidewall of the housing, the at least one exit port permitting fluid todrain through when in an open position; at least one bleeder port formedon the bottom of the housing, the at least one bleeder port permittingthe fluid to flow through the bottom of the housing; and a valve unitdisposed inside the housing, the valve unit having at least oneregulating mechanism for opening the at least one exit port in responseto fluid pressure acting thereon, each of the regulating mechanismshaving an obstructing member blocking fluid flow through the housing anda compressible bias spring attached to the obstructing member, thecompressible spring having a spring constant permitting compression ofthe spring within a predefined range of fluid pressure, the springbiasing the obstructing member to keep the at least one exit port in aclosed position blocking fluid entering the fluid inlet end from exitingthrough the exit port until fluid pressure is within the predefinedrange, the spring being compressed to the open position when the fluidpressure is within the predefined range; wherein the valve unit providespressure-sensitive, self-regulating drainage of CSF fluid in response topressure of incoming fluid; wherein said obstructing members comprisediscs; and at least a pair of elongated guide rails disposed inside saidhousing each said disc having at least a pair of notches disposed alonga periphery thereof, the notches on each of said discs being slidablymounted to said guide rails for stable reciprocation within saidhousing.
 2. The CSF shunt valve according to claim 1, wherein said atleast one exit port comprises an exit area equal to the cross sectionalarea of the catheter lumen.
 3. The CSF shunt valve according to claim 1,wherein said at least one exit port comprises at least a pair ofelongate exit slots extending along the length of said sidewall.
 4. TheCSF shunt valve according to claim 1, wherein said at least one exitport comprises a plurality of holes defined in said sidewall.
 5. The CSFshunt valve according to claim 4, wherein each said hole defines anarea, the total area of said holes being equal to the cross-sectionalarea of the catheter lumen.
 6. The CSF shunt valve according to claim 4,wherein said at least one regulating mechanism comprises a plurality ofregulating mechanisms, each regulating mechanism being responsive to adifferent range of pressure increasing in value from the inlet end tothe bottom of the housing, each regulating mechanism being seriallyconnected to each other within the housing.
 7. The CSF shunt valveaccording to claim 6, wherein said plurality of regulating mechanismscomprises a first obstructing member, a first spring serially connectedto the first obstructing member, a second obstructing member seriallyconnected to the first spring, a second spring serially connected to thesecond obstructing member, a third obstructing member serially connectedto the second spring, and a third spring serially connected to the thirdobstructing member, each spring being compressible within a differentfluid pressure range, the fluid pressure range for each of the springsbeing discontinuous with the adjacent spring.
 8. The CSF shunt valveaccording to claim 7, wherein said first spring is compressible within arange of about 3-5 mm Hg, said second spring is compressible within arange of about 7-9 mm Hg, and said third spring is compressible within arange of 11 mm Hg and above.
 9. The CSF shunt valve according to claim1, wherein at least one of said discs is solid.
 10. The CSF shunt valveaccording to claim 9, wherein at least one of said discs includes atleast one hole defined therein.
 11. The CSF shunt valve according toclaim 1, further comprising an elongate, outer sleeve surrounding andprotecting said housing, said outer sleeve having a plurality ofreinforcing annular rings disposed along the length of the outer sleeve,each of the rings having a plurality of members extending radiallyinward and attached to said housing.
 12. The CSF shunt valve accordingto claim 1, wherein said compressible bias spring comprises a pluralityof consecutive spring sections, each spring section having a springconstant different from each other, each spring section permittingcompression of the spring within a predefined range of fluid pressure,said range of pressure for each of the spring sections being differentand discontinuous with the adjacent spring section.
 13. A CSF shuntvalve, comprising: an elongate, hollow housing adapted to be attached toa catheter, the housing having a sidewall and a bottom; a plurality ofexit ports formed in the sidewall of the housing, the exit portspermitting fluid to drain through; a plurality of bleeder ports formedon the bottom of the housing, the plurality of bleeder ports permittingthe fluid to flow through the bottom of the housing; and a valve unitdisposed inside the housing, the valve unit having at least oneregulating mechanism for opening the at least one exit port in responseto fluid pressure acting thereon, each of the regulating mechanismshaving an obstructing member blocking fluid flow through the housing anda compressible bias spring attached to the obstructing member, thecompressible spring having a spring constant permitting compression ofthe spring within a predefined range of fluid pressure, the springbiasing the obstructing member to keep the at least one exit port in aclosed position blocking fluid entering the fluid inlet end from exitingthrough the exit port until fluid pressure is within the predefinedrange, the spring being compressed to the open position when the fluidpressure is within the predefined range, the range of pressure for eachof the springs being different and discontinuous with the adjacentspring; wherein the valve unit provides pressure-sensitive,self-regulating drainage of CSF fluid in response to pressure ofincoming fluid; wherein said obstructing members comprise discs; and atleast a pair of elongated guide rails disposed inside said housing eachsaid disc having at least a pair of notches disposed along a peripherythereof, the notches on each of said discs being slidably mounted tosaid guide rails for stable reciprocation within said housing.
 14. A CSFshunt valve, comprising: an elongate, hollow housing adapted to beattached to a catheter, the housing having a sidewall and a bottom; aplurality of exit ports formed in the sidewall of the housing, the exitports permitting fluid to drain through; a plurality of bleeder portsformed on the bottom of the housing, the plurality of bleeder portspermitting the fluid to flow through the bottom of the housing; and avalve unit disposed inside the housing, the valve unit having at leastone regulating mechanism for opening the at least one exit port inresponse to fluid pressure acting thereon, each regulating mechanismhaving an obstructing member blocking fluid flow through the housing anda compressible bias spring attached to the obstructing member, thecompressible spring having a plurality of consecutive spring sections,each spring section having a spring constant different from each other,each spring section permitting compression of the spring within apredefined range of fluid pressure, the spring biasing the obstructingmember to keep the at least one exit port in a closed position blockingfluid entering the fluid inlet end from exiting through the exit portuntil fluid pressure is within the predefined range of each springsection, the spring being compressed to the open position when the fluidpressure is within the predefined range of each spring section, therange of pressure for each of the spring sections being different anddiscontinuous with the adjacent spring section; wherein the valve unitprovides pressure-sensitive, self-regulating drainage of CSF fluid inresponse to pressure of incoming fluid; wherein said obstructing memberscomprise discs; and at least a pair of elongated guide rails disposedinside said housing each said disc having at least a pair of notchesdisposed along a periphery thereof, the notches on each of said discsbeing slidably mounted to said guide rails for stable reciprocationwithin said housing.